How the ratings are earned
Impact ratings come from UL 2218. In the test, steel balls of increasing size are dropped onto the roofing, typically twice in the same spot, and the material is checked for cracks or tears. There are four classes. Class 4 is the highest.
| Class 3 | Class 4 | |
|---|---|---|
| Test ball | 1.75 inches | 2 inches |
| Protection | Strong improvement over standard shingles | The top rating in the test |
| Insurance discounts | Less commonly offered | Offered by some insurers |
| Cost | Moderate premium | Higher premium |
When Class 4 makes sense
- Your insurer offers a discount for Class 4 roofs
- You've replaced a roof after hail before
- You plan to stay in the home for many years
- You want the strongest protection available in a shingle
When Class 3 is a smart middle ground
- You want better hail protection without the top-tier price
- Your insurer doesn't offer an impact discount
- You're balancing a roof upgrade with other projects
First step: Call your insurance agent and ask whether they discount Class 4 roofs and what proof they need. That answer often settles the decision.
Beyond shingles
If maximum durability is the goal, stone coated steel often carries a Class 4 rating along with a much longer lifespan. See also impact-resistant shingles.
Common questions
Is Class 4 always worth it over Class 3?
Not always. If your insurer offers a Class 4 discount, or you've replaced roofs after hail before, Class 4 often makes sense. Otherwise Class 3 is still a real improvement over standard shingles.
Do impact ratings affect appearance?
No. Both are available as attractive architectural shingles in a full range of colors.
Does a Class 4 rating mean my roof can't be damaged?
No. It means the shingle passed a standardized impact test. Very large hail can still damage any roof.